Tipos de diseños de los estudios clínicos y epidemiológicos

Abstract

Many clinician reports that they cannot read the medical literature critically, to address this difficulty, we provide a clinical Research for clinicians and researches alike. Epidemiologic and Clinical Research fall into two categories: Observational and experimental based on wether the investigator not assigns or assigns the exposition. Observational studies can be either descriptiveor analytical. Descriptive studies such as case report and case- series reports do not have a comparison group. In this way in these kinds of studies the investigator cannot examine the association and very often they ignore it. Cross- sectional studies are like a snapshot, which measure both exposure and outcome at one time point. Analytical studies feature a comparison group (control), whereas descriptive studies do not. Within analytical studies, cohort track peoples forward in time from exposition to outcome. By contrast, case- control studies work in reverse tracking back from outcome to exposition. Experimental trials can also be subdivided into two: non-randomized and randomized In this review we define and explain the different designs of epidemiologic and clinical studies in extensive form for a better understood of them. Also explain the association measures, such as relative risk and odds ratio, which are the preferred way of expressing results of dichotomous outcome e.g, sick versus healthy.